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    <title>Document</title>
    <script>
        var a=4;
        var b=2;
        var c=a;//c=4
        var d=a+b;//d=4+2=6
        b=c+d;//b=4+6=10
        console.log(a);//4
        console.log(b);//10
        console.log(c);//4
        console.log(d);//6
    </script>
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